JPH10125589A - Scanning type exposure equipment, and device manufacture using the equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a more precise alignment than conventional ones, when a pattern has been formed already in the pattern transcription region of the surface of a second object by a scanning exposure, performing the alighnment of a first object withg the second object usinf the last scanning exposure direction of the patterns as an information. SOLUTION: In the alignment of a first object 1 (mask) with a second object 3 (wafer), observing mask marks 41 on the mask 1 in photoelectrically, the obtained signals are processed by sensing means 101 to send the processed signals to a computation processing circuit 102 as positional information. The positional information of a mask stage 4 is also sent from drive controlling means 103 to the circuit 102 to be stored in it correspondingly to the positional informations of the mask marks 41. The positional information of masks 42 on the wafer 3 and the positional information of a wafer stage 5 are also sent to the computation processing circuit 102 to be stored in it. On the wafer 3, a plurality of pattern transcription regions 22 are present, and all the transcription regions 22 are measured repeatedly to obtain positional information. Therefor, the alignment is performed using the last scanning exposure direction of a selected one of the pattern transcription regions 22 as an information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus and a device manufacturing method using the same, and relates to an IC, an LSI,
In a lithography process for manufacturing a device such as a CCD, a magnetic head, a liquid crystal panel, etc., after positioning a reticle (mask) as a first object and a wafer as a second object, both are scanned synchronously. By doing so, the pattern on the reticle surface is sequentially scanned and exposed on the wafer surface to manufacture a highly integrated device.

[0002]

2. Description of the Related Art In recent years, the integration of semiconductor devices such as ICs and LSIs has been increasing at an ever-increasing rate. As a result, an arc-shaped exposure area has been used as a projection exposure apparatus which is at the center of fine processing technology for semiconductor wafers. A 1: 1 projection exposure apparatus (mirror projection aligner) that exposes a 1 × mirror optical system while scanning the mask and the photosensitive substrate while scanning the mask and the photosensitive substrate, and forms a pattern image of the mask on the photosensitive substrate using a refractive optical system. There has been proposed a reduction projection exposure apparatus (stepper) for exposing an image by a step-and-repeat method.

Recently, various step-and-scan type scanning projection exposure apparatuses (exposure apparatuses) have been proposed which can obtain a high resolution and can enlarge a screen size.
In this scanning type exposure apparatus, a pattern on a reticle surface is illuminated by a slit light beam, and a pattern illuminated by the slit light beam is exposed and transferred onto a wafer by a scanning operation via a projection system (projection optical system). .

On the other hand, in a projection exposure apparatus, a pattern on a reticle surface is projected onto a wafer surface after relative positioning between a reticle and a wafer. Has become an important factor in achieving higher integration. As a positioning method at this time, a so-called global alignment method in which a representative shot is selected and measured from a plurality of pattern transfer areas (exposure transfer shots) on the wafer to obtain wafer position information is a point of throughput. It is advantageous and recommended.

[0005]

In recent years, the progress of fine processing of semiconductor devices has been remarkable, and a highly accurate method for positioning a reticle and a wafer has been demanded. In general, if the positioning is performed with higher accuracy, various factors which have not been a problem in the past are caused as error factors.

In a scanning type projection exposure apparatus, a wafer on which a pattern is printed is, as shown by an arrow in FIG. 4, a wafer stage whose scanning exposure axis is positive in a transfer shot (SH1 to SHn) on the wafer 3 surface. Transfer shots printed while scanning in the direction (upward in the Y direction in FIG. 4) and transfer shots printed while scanning in the opposite direction (downward in the Y direction in FIG. 4) are mixed. This is because, in order to perform scanning exposure in all shots in the same direction, it is necessary to return the wafer stage and the mask stage once and then perform exposure, which lowers productivity. Therefore, scanning exposure is performed in both forward and reverse directions as an essential item. It is.

In a scanning type exposure apparatus, the difference in the pattern transfer position in the scanning direction is adjusted as much as possible. However, in practice, the difference in the scanning direction remains slightly. The position difference (distance) due to the difference in the scanning direction indicated by ds in FIG. 4 was not problematic in accuracy at the level of the conventional alignment, but can be ignored in view of the high accuracy of the alignment in the future. It's gone.

In the conventional wafer alignment method using the global formula, without taking into account the difference in the position of the shot due to the difference in the scanning direction, as shown in FIG.
H1 to SH8) were selected, and the shot arrangement grid was the same for all shots, and the measurement results were arithmetically processed to derive the position information of each shot. For this reason, in order to perform high-accuracy alignment, the positional difference (ds) at this time causes a significant decrease in alignment accuracy.

According to the present invention, after aligning a reticle (first object) with a wafer (second object), a pattern on the reticle surface is scanned and exposed on the wafer (second object) by a projection optical system. When performing repetitive scanning projection exposure using the method, alignment between the reticle and the wafer is performed using information on the scanning exposure direction of the wafer surface, thereby enabling high-accuracy alignment, thereby achieving high resolution. Moreover, it is an object of the present invention to provide a scanning type exposure apparatus which facilitates projection exposure on a large screen and a method for manufacturing a device using the same.

[0010]

According to the present invention, there is provided a scanning type exposure apparatus, comprising: (1-1) illuminating a pattern on a first object surface mounted on a first movable stage with an illumination light beam from an illumination system; The pattern on the first object surface is placed on the second movable stage by the projection optical system, and the first movable stage and the second movable stage are placed on the second object surface that has been aligned with the first object. In a scanning exposure apparatus that performs projection exposure while relatively scanning in synchronization with a speed ratio corresponding to the projection magnification of the projection optical system, a pattern is already formed on a pattern transfer area on the second object surface by scanning exposure. In this case, the first object and the second object are aligned using information on the pre-scanning exposure direction.

Particularly, (1-1-1) when a plurality of pattern transfer areas exist on the second object plane, the first object and the second object
Positioning with the object is performed using information on the pre-scanning exposure direction for each pattern transfer area, (1-1-2) a plurality of pattern transfer areas are present on the second object plane, Correcting the alignment information between the first object and the second object by using information in each of the pre-scanning exposure directions of at least three pattern transfer areas selected from the plurality of pattern transfer areas; (1- 1-3) When detecting a plurality of pieces of position information within the one pattern transfer area to measure the shape information of the pattern transfer area, the shape of the pattern transfer area is determined using information for each pre-scanning exposure direction. Information is corrected, and the first object and the second object are aligned using the shape information. (1-1-4) The same direction as the pre-scanning exposure direction of the pattern transfer area And projection exposure of the pattern on the first object plane. To have.

The method for manufacturing a device according to the present invention has a structure (1)
After aligning the reticle and the wafer using the scanning exposure apparatus of -1), the pattern on the reticle surface is projected and exposed on the wafer surface, and then the device is exposed to the wafer through a developing process. It is characterized by being manufactured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a scanning exposure apparatus according to a first embodiment of the present invention.

In this embodiment, a mask (also referred to as a reticle) 1 as a first object and a wafer 3 as a second object
The projection exposure is performed while scanning (scanning) with a predetermined speed ratio while synchronizing with the image forming magnification of the projection optical system 2.

In FIG. 1, a mask 1 on which an exposure pattern is formed includes a laser interferometer (not shown) and a drive control unit 1.
The mask stage is mounted on a mask stage (first movable stage) 4 that is driven and controlled in the X direction by 03. The mask stage 4 is driven in the X direction while keeping the position in the Z direction constant with respect to the projection optical system 2. Wafer 3 as photosensitive substrate
Is mounted on a wafer stage (second movable stage) 5 that is driven and controlled in the X and Y directions by a laser interferometer (not shown) and drive control means 103. Further, the position and inclination of the wafer stage 5 in the Z direction can be driven and controlled with respect to the projection optical system 2.

The mask 1 and the wafer 3 are placed at optically conjugate positions via the projection optical system 2, and a slit-like exposure light beam 6 long in the Y direction is irradiated on the mask 1 from an illumination system (not shown). Is formed. The exposure light beam 6 on the mask 1 forms a slit-like exposure light beam 6 a on the wafer 3 having a size that is larger than the projection magnification of the projection optical system 2. In the scanning exposure apparatus, the slit-shaped exposure light fluxes 6 and 6a
Then, both the mask stage 4 and the wafer stage 5 are moved in the X direction synchronously at a speed ratio corresponding to the optical magnification, so that the slit-shaped exposure light beams 6 and 6 a The scanning projection exposure is performed by scanning the pattern transfer area 22 of FIG.

Next, a method of aligning the mask 1 with the wafer 3 in the present embodiment will be described.

First, a mask mark 41 disposed near the pattern 21 on the mask 1 is photoelectrically observed using the observation microscope 7, and a signal obtained from the observation is used as a mark detection means 1.
01 and is sent to the arithmetic processing circuit 102 as position information of the mask mark 41. The position information of the mask stage 4 at the time of observing the mask mark 41 is stored in the drive control unit 10.
3 is sent to the arithmetic processing circuit 102 and the mask mark 41
Is stored in association with the position information.

Next, the pattern transfer area 22 on the wafer 3
Measure the location information. In the present embodiment, the position information of the pattern transfer area 22 on the wafer 3 is measured using the observation microscope 7 for observing the mask pattern 41. However, a dedicated observation microscope may be used. Since it is not necessary to use a so-called complete off-axis microscope, a so-called complete off-axis microscope may be used.

The method of measuring the position information of the pattern transfer area 22 on the wafer 3 is the same as that of the mask pattern 41, and the pattern transfer area 22 on the wafer 3 is The wafer mark 42 arranged in the vicinity is observed photoelectrically. Then, the signal obtained from the signal is processed by the mark detection means 101 and sent to the arithmetic processing circuit 102 as the position information of the wafer mark 42. The position information of the wafer stage 5 at the time of observation is sent from the drive control means 103 to the arithmetic processing circuit 102 and stored in correspondence with the position information of the wafer mark 42. Wafer 3
In many cases, there are a plurality of pattern transfer areas 22 on the upper side. In this case, the above measurement is repeated for the selected (at least three) pattern transfer areas 22 so that all the patterns in the entire wafer 3 are obtained. The global alignment is performed so that the position information of the transfer region 22 is obtained.

The present embodiment is characterized in that the direction in which the measurement shot (pattern transfer region) selected in the global alignment is scanned and exposed at the time of the immediately preceding process manufacturing (pre-scanning exposure direction) is used as information. . At this time, information can be obtained by a key input to the apparatus by the apparatus operator, or, if a pre-process is created by the same apparatus or the same model, in the scanning direction on the apparatus side, It is possible to automatically determine whether the transfer area 22 has been exposed.

FIG. 2 is an explanatory view showing how a measurement shot on the surface of the wafer 3 is selected in the global alignment according to the present embodiment.

In FIG. 1, 32 pattern transfer areas 22 are formed on the wafer 3, and 12 shots are selected as global alignment measurement shots. The selected measurement shot is taken as the forward direction (upward in the figure) as the scanning exposure direction during the pre-exposure and SHU
Six shots from 1 to SHU6 are equally distributed as six shots from SHD1 to SHD6 as the direction opposite to the scanning exposure direction (downward in the figure). In a conventional alignment device,
All the 12 shot information was processed equally. On the other hand, in the present embodiment, the position information grid GSU is obtained by processing the position information of the pattern transfer area 22 that is exposed in the forward direction as the scanning exposure direction at the time of the pre-exposure by using six shots SHU1 to SHU6. . Also, the pattern transfer area 22 exposed in the reverse direction as the scanning exposure direction during the pre-exposure.
Is processed by six shots SHD1 to SHD6 to obtain a position information grid GSD.

When scanning and exposing the pattern 21 to each pattern transfer area 22, the two positional information grids GS
Exposure is performed using one of U and GSD. If the pattern transfer area 22 has been exposed in the forward direction in the previous process, an instruction is issued from the arithmetic processing circuit 102 to the drive control means 103 using the position information grid GSU. The exposure is performed by controlling the positions of the mask stage 4 and the wafer stage 5 by the drive control means 103. If the pattern transfer region 22 is exposed in the reverse direction in the previous process, the position information grid G
From the arithmetic processing circuit 102 to the drive control means 10
3 is instructed.

The drive control means 103 controls the positions of the mask stage 4 and the wafer stage 5 so that the mask and the wafer are positioned and exposed. By using the two position information gratings GSU and GSD at the time of scanning exposure as described above, the position error ds of the pattern transfer region 22 caused by the difference in the scanning exposure direction in the previous process can be satisfactorily corrected, and highly accurate projection exposure can be performed. Is going.

Next, a second embodiment of the present invention will be described.

In the present embodiment, when aligning a wafer, a plurality of pieces of position information are measured within one of a plurality of pattern transfer areas, and shape information of the pattern transfer area is measured for each pre-scanning exposure direction. , Stored and corrected when scanning projection exposure is performed on the pattern on the mask.

As shown in FIG. 3, errors caused by the pre-scanning exposure direction are caused not only by the displacement of the center of the pattern transfer area, but also by the entire pattern transfer area being rotated, enlarged, or reduced, thereby causing the overall shape deformation. Error also occurs. This error is also measured and corrected to establish a more accurate matching relationship with the pattern transfer area.

More specifically, in this embodiment, the measurement shot S for global alignment in the first embodiment is used.
Multiple wafer marks in each shot of HU1-6 and SHD1-6 (corresponding to marks 421-426 in FIG. 3)
Is measuring location information. As the shape information of the pattern transfer region 22 that is exposed in the forward direction as the scanning exposure direction at the time of the pre-exposure, the measurement result is processed by six shots SHU1 to SHU6 to obtain a shape information grid LSU.
The shape information of the pattern transfer area 22 exposed in the reverse direction as the scanning exposure direction during the pre-exposure includes SHD
The shape information lattice LSD is obtained by processing with six shots from 1 to SHD6.

When scanning and exposing the pattern 21 to each pattern transfer area 22, the two shape information grids LS
Exposure is performed using one of U and LSD. If the transfer area 22 has been exposed in the previous step in the forward direction, the drive control unit 1
03 is instructed. The exposure is performed by controlling the positions of the mask stage 4 and the wafer stage 5 by the drive control means 103. If the pattern transfer region 22 has been exposed in the previous process in the reverse direction, an instruction is issued from the arithmetic processing circuit 102 to the drive control means 103 using the shape information grid LSD. The drive control means 103 controls the positions of the mask stage 4 and the wafer stage 5 so that the mask and the wafer are positioned and exposed. As described above, by using the two shape information gratings LSU and LSD at the time of scanning exposure, the shape error of the pattern transfer region 22 caused by the difference in the scanning exposure direction in the previous process can be satisfactorily corrected.
High-precision projection exposure is performed.

Next, a third embodiment of the present invention will be described.

This embodiment is characterized in that the pattern on the mask is projected and exposed in the same direction as the pre-scanning exposure direction of the pattern transfer area. As shown in Embodiments 1 and 2,
In the present invention, it is possible to measure the deviation ds of the pattern transfer area on the wafer side caused by the difference in the direction of the pre-scanning exposure. On the other hand, a similar error may occur during scanning projection exposure. This error is considered to have a certain tendency in the same scanning projection exposure apparatus.

Therefore, in this embodiment, the pattern on the mask is subjected to scanning projection exposure in the same direction as the pre-scanning exposure direction. If an error caused by the scanning exposure direction of the scanning exposure apparatus is common to all the apparatuses, the overlay error between the pattern and the pattern transfer area can be improved only by aligning the scanning exposure direction. This embodiment may be applied simultaneously with the first and second embodiments, and according to this, further effects can be expected.

Next, an embodiment of a method of manufacturing a semiconductor device using the above-described projection exposure apparatus will be described.

FIG. 5 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD).

In this embodiment, in step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2
In (mask production), a mask on which a designed circuit pattern is formed is produced.

On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like.

In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 6 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, a highly integrated device can be easily manufactured.

[0044]

As described above, according to the present invention, after the reticle (first object) and the wafer (second object) are aligned (aligned), the pattern on the reticle surface is projected onto the wafer by the projection optical system. When repetitive scanning projection exposure is performed on the (second object) using the scanning exposure method, the reticle and the wafer are aligned using information on the scanning exposure direction on the wafer surface, thereby achieving high-accuracy alignment. Accordingly, it is possible to achieve a scanning exposure apparatus and a device manufacturing method using the scanning exposure apparatus, which have high resolution and facilitate projection exposure to a large screen.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method of selecting a transfer shot to be measured when the present invention is applied.

FIG. 3 is an explanatory diagram according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of conventional selection of a transfer shot to be measured.

FIG. 5 is a flowchart of a device manufacturing method of the present invention.

FIG. 6 is a flowchart of a device manufacturing method according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 mask 2 projection optical system 3 wafer 4 mask stage 5 wafer stage 6 slit exposure light beam 7 observation microscope 21 device pattern 22 pattern transfer area 41 mask mark 42 wafer mark 101 mark detection means 102 arithmetic processing circuit 103 drive control means 421 to 426 Wafer mark

Claims (6)

[Claims] An illumination system for illuminating a pattern on a first object surface mounted on a first movable stage with an illumination light beam from the illumination system;
A second optical system in which the pattern on the object surface is placed on the second movable stage by the projection optical system and is aligned with the first object.
A scanning exposure apparatus for projecting and exposing while relatively scanning the first movable stage and the second movable stage on an object plane at a speed ratio corresponding to a projection magnification of the projection optical system; If a pattern is already formed in the pattern transfer area on the object surface by scanning exposure, the first
A scanning exposure apparatus, wherein the positioning of an object and a second object is performed using information on a pre-scanning exposure direction. 2. When there are a plurality of pattern transfer areas on the second object plane, the alignment between the first object and the second object is performed using information on a pre-scanning exposure direction for each pattern transfer area. 2. The scanning exposure apparatus according to claim 1, wherein the scanning exposure is performed. 3. A plurality of pattern transfer areas are present on the second object plane, and the information on each of at least three pattern transfer areas selected from the plurality of pattern transfer areas in each pre-scanning exposure direction is used. 3. The scanning exposure apparatus according to claim 1, wherein alignment information between the first object and the second object is corrected. 4. When detecting a plurality of pieces of position information within the one pattern transfer area to measure the shape information of the pattern transfer area, the information of the pre-scanning exposure direction is used to measure the shape information of the pattern transfer area. 3. The scanning exposure apparatus according to claim 1, wherein the shape information is corrected, and the first object and the second object are aligned using the shape information. 5. The scanning type according to claim 1, wherein a pattern on the first object plane is projected and exposed in the same direction as the pre-scanning exposure direction of the pattern transfer area. Exposure equipment. 6. A pattern on a reticle surface is projected and exposed on a wafer surface by using the scanning exposure apparatus according to claim 1 after aligning a reticle with a wafer. A device manufacturing method for manufacturing the device through a developing process of the wafer thereafter.